Traditionally, these implants can be of the type comprising an elongate hollow body which is inflatable by means of a suitable fluid, for example physiological saline. The surgeon places this hollow body, in an open position, around a segment of the digestive tract situated, for example, between the abdominal part of the esophagus and the stomach.
The surgeon then connects the two ends of the implant to each other in order to lock the resulting ring in a size corresponding to a basal level of constriction of the stomach. The surgeon can then regulate as necessary the level of constriction, hence the weaning of the patient, by inflating/deflating the implanted closed ring from outside the body of the patient with the aid of a syringe and an implantable chamber with septum connected to the ring via a catheter, this regulation being carried out during normal hospitalization.
The technical problems associated with these inflatable and adjustable gastric implants are in particular those mentioned below:                a. The ease of implantation for the surgeon, which directly influences the comfort and health of the patient.        b. Further to problem (a), the possibility of performing the implantation by laparoscopy is an important advantage.        c. Lasting biocompatibility of the implant.        d. The stresses resulting from the ingestion of food can cause movement of the ring. This can be avoided by means of sutures, although the implanted ring should ideally have a stable position without recourse to this aggressive means.        e. Visibility to X-rays (radiopacity) is a desired advantage for the implant.        f. It is also desirable that this type of inflatable gastric implant is not subject to a phenomenon of occlusion, by the inner wall, of the inflation opening which is connected to the catheter and is arranged on the outer wall of the hollow band, particularly during deflation of this hollow band by aspiration of the inflation fluid.        g. The safety and reliability of closing the hollow band in a ring shape around the stomach of the patient is also a factor in determining the efficacy of the implant. To this end, it is therefore desirable to obtain optimal locking of this closed position.        h. The demands of serial production according to high quality standards and at the best possible cost are also at the heart of the problems addressed by the present invention.        i. In order to ensure a centripetal deformation of the closed gastric ring by inflation, it is important that the back or the outer wall is reinforced in relation to the inner wall, of which the outer face is in contact with the digestive tract after implantation.        
French patent FR2887436 B1 discloses an inflatable gastric belt comprising an elongate tubular body made of elastically deformable, flexible material, this body defining an inflatable leaktight chamber and having a back and a working face. This belt also comprises connecting means which are arranged in relation to two ends of the tubular body and allow the gastric belt to be closed in the shape of a ring, the working face being arranged on the inside of the ring. This belt finally comprises an inflation catheter which is intended to be connected to inflation means, and which is connected in a leaktight manner to the inflatable chamber via an inflation orifice formed in the back of the elongate tubular body. The inner face of the back of the tubular body has eight protuberances intended to provide support for the inner wall of the chamber near the inflation orifice formed in the back of the tubular body.
The gastric belt according to French patent FR2887436 B1 can be perfected in respect of all or some of the abovementioned technical problems (a) to (i), in particular as regards (a) the ease with which the surgeon places the implant around the stomach, and, more particularly, for introducing the catheter into the loops in order to form the ring around the stomach in a loop formation.
Referring to FIG. 1, French patent FR2903297 discloses a gastric belt 1 comprising a tubular body 2 defining a leaktight and inflatable chamber 3 and having, seen from above, the general shape of a C, as is shown in the attached FIG. 1, which is a cross section in the medial longitudinal plane of the gastric belt according to French patent FR2903297; when not in use and in the deflated state, the tubular body 2 has a generally flat shape and a rectangular cross section. The gastric belt also comprises an inflation catheter 14 via which an inflation orifice 16, formed in the back 4 of the tubular body 2, is connected to inflation means. One of the ends of the catheter 14 is intended to be passed through two arches 20, 21 arranged on the back 4 of the tubular body 2, in the curved free end part thereof, in order to form a ring by looping around the stomach. The end part 18p of the catheter 16 comprises two fir-tree-shaped non-return means 22, which are intended to cooperate with the arches 20, 21 in order to lock the ring in the closed position. The end part 18p of the catheter 16, which comprises these non-return fir trees 22, is bent about an angular sector β of 45 to 75° of the same radius of curvature and in the continuation of the arc of a circle formed by the tubular body on a tubular sector α of between 160 and 230° C. This gastric belt according to French patent FR2903297 B1 can also be perfected in respect of all the abovementioned technical problems a to i, in particular as regards the ease with which the surgeon places it around the stomach, in particular for engaging the proximal free end of the catheter in the loops provided on the distal end part of the hollow body intended to form a ring by looping.
The application WO03/059215 A1 describes a gastroplasty ring preformed in a C shape when not in use, made of an elastomeric material and connected to an inflation catheter. This relatively rigid toric ring is intended to be closed around the stomach of the patient. The ring has an inflatable annular compression chamber which is delimited by a dorsal (external) U-shaped reinforcement on which so-called “lateral” walls (inner part) are overmolded in order to form an assembly which is presented as being “in one piece”, but which in reality is not, since it is composed of several overmolded components (discontinuity of the materials). The dorsal reinforcement is made of a material of greater hardness than that of the inner part of the ring. The closure means with a single lock consist of a female means formed by a collar integrally connected to the end of the ring and by a male means formed by an endpiece integrally connected to the other end of the ring. When not in use, this collar and this endpiece are not in the continuation of the pre-formed C-shaped ring.
This ring has the disadvantage of not really being in one piece, of being difficult to produce, and of having only a single closing lock, which increases the risks of accidental opening and the complications associated therewith.
Moreover, this ring has a not inconsiderable thickness and a certain rigidity due to its method of manufacture by preforming. Its placement around the stomach is an awkward and risky operation since it requires the entire ring to be passed under (behind) the stomach, with risks of damage to the spleen and/or the portal vein near the stomach. In addition, the rigid endpiece provided for closing this ring protrudes in the locked position and also has rigid tongues, such that there are real risks of injury to the organs around the stomach of the patient.
In this context, the object of the present invention is to improve the surgical implants of the types described in the patents FR2887436 B1, FR2903297 B1 and WO 03/059215 A1 as regards the abovementioned technical problems.
In particular, the inflatable and adjustable gastric band according to the invention is aimed at ensuring the best possible comfort and safety of the patient, in particular by making the work of the surgeon easier in order to permit rapid and safe placement of the ring around a given segment of the digestive tract. The closed ring implanted in this way must be stable in its position, non-aggressive and effective.
In order to optimize the inflation, hence the adjustment of the level of constriction, the gastric band according to the invention must have a reinforcement of the dorsal outer wall such that the inflation is effected optimally in a centripetal manner.
It is also desirable that deflation does not cause the inflation orifice of the outer wall to be occluded by the inner wall as a result of a reduced-pressure phenomenon during the deflation.
The present invention is also aimed at optimizing industrial manufacture with high demands on quality and economy.